Erupting ‘Nanovolcanoes’ For Drug Delivery

Photonics.comJun 2013
RALEIGH, N.C., June 14, 2013 — “Nanovolcanoes” carved out of a synthetic polymer with UV light can store and release precise amounts of materials, a feat suitable for drug-delivery technologies, its creators say.

North Carolina State University researchers created the nanovolcanoes by placing transparent, spherical nanoparticles directly on a thin film that, when shone with UV light, underwent a chemical change. The film was submerged into a liquid solution that washed away the parts of the film exposed to the light, yielding a small mound with a hollow core.

“We can control the pattern of light by changing the diameter of the nanoparticle spheres, or by changing the wavelength of the light that we shine through the spheres,” said Xu Zhang, a doctoral student in mechanical and aerospace engineering at NC State. “That means we can control the shape and geometry of these structures, such as how big the cavity of the nanovolcano will be.”

Cross-section of a nanovolcano carved using UV light. The nanovolcanoes have precisely measured hollow cores and openings at their “mouth,” which make them a good candidate for drug-delivery mechanisms, its developers at North Carolina State University say. Courtesy of Chih-Hao Chang, NC State.
A highly accurate computer model was developed to predict the shape and dimensions of the nanovolcanoes based on the diameter of the nanoscale sphere and the wavelength of light.

Because these structures have precisely measured hollow cores, and precisely measured openings at the “mouth” of the nanovolcano, they are a good candidate for drug-delivery mechanisms.

By controlling the cavity’s size, the researchers are able to control the size of the drug payload. And, like a volcano, the structures have a hole at the top, the size of which controls the rate of release.

“The materials used in this process are relatively inexpensive, and the process can be easily scaled up,” said assistant professor of mechanical and aerospace engineering Dr. Chih-Hao Chang. “In addition, we can produce the nanovolcanoes in a uniformly patterned array, which may also be useful for controlling drug delivery.”

The investigators are now working to improve their understanding of the nanovolcano’s release rate, including how quickly nanoparticles of different sizes will “escape” from different-sized volcano mouths.

“That’s essential information for drug-delivery applications,” Chang said. “It’s exciting to take our understanding of how light scatters by particles and apply it to nanolithography in order to come up with something that could actually help people.”

The research — supported by a NASA Early Career Faculty Award and the National Science Foundation’s ASSIST Engineering Research Center at NC State — appeared in ACS Nano (doi: 10.1021/nn402637a).